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Finding the Fourth Proportional to 39.64, 54.78 and 31.48

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Solution

The fourth proportional to 39.64, 54.78 and 31.48 is: 43.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.64 : 54.78 = 31.48 : x
  2. Step 2: Convert to fraction form
    39.64/54.78 = 31.48/x
  3. Step 3: Cross multiply
    39.64x = 54.78 × 31.48
  4. Step 4: Simplify right side
    39.64x = 1,724.47
  5. Step 5: Solve for x
    x = 1,724.47/39.64
  6. Step 6: Final answer
    x = 43.50

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.